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Table 3 CYP1A2 activity and risk factors for breast cancer: premenopausal women

From: Cytochrome P450 1A2 (CYP1A2) activity and risk factors for breast cancer: a cross-sectional study

Variable β (SE) F P Quartiles (mean CMR [95% confidence interval]) P for trend
     Q1 Q2 Q3 Q4  
Age (years) 0.001 (0.007) 0.01 0.93      
Age at first birth (years)2 0.16 (0.21) 0.56 0.46      
Age at menarche (years) 0.03 (0.03) 1.80 0.18 6.11 (5.12–7.29) 6.55 (5.49–7.81) 7.39 (5.84–9.35) 6.62 (5.03–8.71) 0.16
BMI (kg/m2)2 -0.43 (0.19) 5.05 0.03 7.76 (6.32–9.53) 6.11 (5.09–7.33) 6.17 (5.02–7.57) 6.16 (4.89–7.76) 0.04
WHR 1.26 (0.70) 3.23 0.07 5.89 (4.80–7.24) 6.01 (4.90–7.37) 6.46 (5.31–7.86) 7.20 (5.87–8.83) 0.06
Caffeine (mg/day)1 0.020 (0.007) 6.32 0.01 5.42 (4.49–6.54) 6.37 (5.29–7.68) 6.28 (5.17–7.64) 6.94 (5.84–8.24) 0.02
Alcohol (kcal/day)2 0.03 (0.02) 2.13 0.15 5.17 (4.33–6.16) 5.17 (4.29–6.23) 5.88 (4.85–7.12) 6.12 (5.03–7.45) 0.05
Cholesterol (mg/day)2 0.09 (0.08) 1.29 0.26      
Total energy (kcal/day)1 0.01 (0.01) 6.05 0.02 5.73 (4.70–6.98) 6.18 (5.00–7.64) 6.58 (5.46–7.93) 6.81 (5.56–8.33) 0.06
Carbohydrate (g/day)1 0.02 (0.02) 2.26 0.14 5.87 (4.84–7.13) 6.75 (5.51–8.26) 6.30 (5.13–7.74) 6.63 (5.45–8.07) 0.34
Fat intake (g/day)1 0.05 (0.02) 4.33 0.04 6.04 (5.20–7.01) 6.94 (5.98–8.05) 6.38 (5.46–7.45) 7.01 (6.03–8.15) 0.25
Protein intake (g/day)2 0.29 (0.11) 7.81 0.006 6.01 (4.97–7.27) 6.74 (5.45–8.33) 6.20 (5.08–7.55) 6.93 (5.65–8.50) 0.28
Total estradiol (pmol/l)3 -0.001 (0.006) 0.01 0.92      
Free estradiol (%)2 -0.05 (0.01) 11.02 0.001 6.62 (5.51–7.96) 7.46 (6.16–9.04) 5.99 (4.90–7.31) 5.16 (4.19–6.35) 0.007
SHBG (nmol/l)4 0.07 (0.02) 10.89 0.001 5.13 (4.16–6.35) 6.09 (4.96–7.46) 7.57 (6.17–9.28) 6.73 (5.64–8.03) 0.004
Progesterone (nmol/l)1 -0.01 (0.02) 0.40 0.53      
FSH (IU/l)2 0.01 (0.04) 0.01 0.91      
GH (μg/l)5 0.01 (0.03) 0.14 0.71      
IGF-1 (ng/ml)6 0.30 (0.22) 1.73 0.19 5.59 (4.59–6.81) 6.59 (5.38–8.06) 7.63 (6.19–9.41) 6.75 (5.41–8.43) 0.07
IGFBP-3 (mg/l)7 -0.14 (0.31) 0.20 0.66      
Insulin (pmol/l)2 0.24 (0.09) 6.91 0.01 5.44 (4.51–6.57) 5.52 (4.49–6.78) 7.16 (5.91–8.68) 7.61 (6.19–9.37) 0.0009
Total cholesterol (mmol/l)2 -0.74 (0.20) 13.84 0.0003 7.37 (5.93–9.17) 6.88 (5.71–8.28) 6.24 (5.14–7.58) 5.64 (4.62–6.89) 0.006
LDL-cholesterol (mmol/l)2 -0.44 (0.15) 8.82 0.004 7.28 (5.91–8.96) 6.77 (5.60–8.19) 6.67 (5.54–8.04) 5.24 (4.30–6.39) 0.004
HDL-cholesterol (mmol/l)2 -0.27 (0.15) 3.35 0.07 7.05 (5.76–8.63) 6.17 (5.06–7.52) 6.83 (5.60–8.32) 5.83 (4.79–7.09) 0.11
Triglycerides (mmol/l)2 -0.02 (0.07) 0.04 0.83      
  1. A total of 146 premenopausal women were studied (n = 101 for age at first birth; n = 144 total estradiol, sex hormone binding globulin [SHBG], alcohol intake, dietary cholesterol, energy intake, carbohydrate intake, total fat intake, and protein intake; n = 145 for free estradiol; n = 143 for growth hormone [GH], insulin-like growth factor [IGF]-1, and IGF binding protein [IGFBP]-3; and n = 142 for caffeine intake). Cytochrome P450 1A2 (CYP1A2) activity is log transformed and modeled as the dependent variable for all models. Models are adjusted for age, smoking status, body mass index (BMI), waist–hip ratio (WHR), and ethnicity. BMI models do not adjust for BMI and WHR models do not adjust for WHR. Quartile means (95% confidence interval) are provided for variables associated with CYP1A2 activity (P ≤ 0.20). 1Square root transformed. 2Log transformed. 3Square root transformed; models adjusted for SHBG. 4Square root transformed; models adjusted for total estradiol levels. 5Log transformed; analyses adjusted for IGF-1 and IGFBP-3. 6Square root transformed; analyses adjusted for growth hormone and IGFBP-3. 7Square root transformed; analyses adjusted for GH and IGF-1. CMR, caffeine metabolic ratio; FSH, follicle-stimulating hormone; HDL, high-density lipoprotein; LDL, low-density lipoprotein; SE, standard error.
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